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1. Rotation

The basic rotation of this build involves rapidly building up Essence through
Bone Spikes and Devour, and then emptying the entire reserve with
a summon of Skeletal MageSingularity. While your resources will constantly
shift between full and empty, never neglect to cast a life-saving
Decrepify on an upcoming pack of enemies, or to sic your melee minions on
a target with Command Skeletons — this will eat up some Essence, but
will be vital for your success. Finally, activate Land of the Dead whenever
it is up for a major fight — this dominant cooldown will all but guarantee
your success.

2. Skills, Runes and Passives

The primary damage dealer and focal point of Rathma set builds are the
Skeletal Mages. Their relatively short 6 second base duration will be
nearly doubled with a combination of Extended Servitude and
Circle of Nailuj's Evol, and their base damage — multiplied by the
Circle of Nailuj's Evol extra summon, Rathma 6-piece and the Jesseth 2-piece.
The rune of choice is Singularity, whose unique property consumes
your entire resource reserve for 3% extra damage per Essence spent. This results
in 930% extra damage per full resource dump on a reasonably equipped character
— a staggering damage difference to the other Skeletal Mage
runes.

You will have a secondary damage dealer in the build in the face of
Command Skeletons, but it will not be focused on through gear and its
impact on overall DPS will diminish as you increase difficulties. They fulfill
an important role as procs of the Jesseth set (Jesseth Skullscythe and
Jesseth Skullshield), so do not neglect to set them on a target every
fresh fight. You will add some crowd control on top through the
Freezing Grasp rune, providing you with regular procs of the worn
Krysbin's Sentence.

In order to maintain this massive resource demand, you will devote three
active skill choices to Essence upkeep.

Your basic source of Essence will be a generator, and while theoretically all
of them will do the job, we recommend Bone Spikes. It is safer with its
longer range vs. Grim Scythe's melee, and is a single cast vs.
Siphon Blood's channeling. Add to that its highest base generation
augmented even further by Reilena's Shadowhook, and it becomes a
no-brainer. You have a significant freedom in your choice of runes; our default
recommendation is the short stun of Sudden Impact for another proc of
Krysbin's Sentence.

The second source of Essence comes from consuming Corpses — a unique
Necromancer resource that is generated largely through combat. You will be using
Devour with the Cannibalize rune to double dip on bonuses —
Health and Essence restoration. Note that due to the skill's lack of casting
animation, you are free to spam as much as you need. While you can keep the rune
on Devouring Aura for convenience, that is best left for the lazier, speed
farming variation.

The final source of Essence generation depends on Devour, but empowers
it greatly. Land of the Dead supplies you with an infinite amount of Corpses
throughout its short duration, allowing you to replenish Health and Essence
almost instantaneously. During its uptime, you will be able to get the maximum
number of Skeletal Mages, all at their maximum power — for a great
boost of damage. Note Land of the Dead's massive cooldown and try to save
it for key fights like Elites and the Rift Guardian. The rune Frozen Lands
will ensure the powerful Krysbin's Sentence proc on all enemies on the
screen for even better damage output.

A utility pick should round out your skill selection, either to keep you safe
or to provide extra damage to the build. While you can stay on an offense curse
like FrailtyScent of Blood for as long as you are comfortable, it is highly
recommended to swap to the defensive powerhouse Decrepify as soon as you
start pushing against your gear limits. Empowered by the stunning utility of the
Dizzying Curse rune and Dayntee's Binding belt, this curse will
soften incoming blows even more effectively than the set-induced damage
reduction. There is a viable alteration of the build that uses
SimulacrumReservoir in this slot, and drops Dayntee's Binding for
The Witching Hour. This variant will result in higher damage output, but
with less consistency and makes the build significantly glassier — be
prepared to fish for favorable rift layouts and monster composition if you try
to take advantage of it.

This concludes the overview of the Active Skills, now let us look through
the Passives.

As previously mentioned, this is a Skeletal Mage-centric build and
everything that augments or extends their power is priority; thus
Extended Servitude takes a firm slot in your passive selection for the
1.5 sec. Mage duration increase.

Following a similar logic, to empower the Singularity rune you
will be taking the flat Essence increase of Overwhelming Essence.

To play to the strengths of your equipped Reaper's Wraps and the
constant spam of Devour, Life from Death will provide you with a
consistent supply of Health Globes. This will greatly improve both the rate and
the average power of your Singularity summons.

You have a degree of freedom in your fourth passive slot. By default, we
recommend Spreading Malediction; it offers an additive damage bonus
against enemies affected by your curse — a boon that scales excellently
with density and is trivial to keep up. Other options include
Swift Harvesting (for the Simulacrum variant), or the Necromancer
cheat death — Final Service.

About the Author

This build is presented to you by Deadset,
one of the very few professional Diablo 3 players.
Deadset regularly publishes video guides on
Youtube and
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see how this and other builds play out in practice.